Effects of friction stir processing and artificial peak aging on erosion resistance of Al-11Si-4Cu-2Ni-0.7Mg cast alloy

Al-11Si-4Cu-2Ni-0.7Mg cast alloy, which contains large amount of coarse second phase particles including eutectic Si, delta (Al3CuNi) and tau(1) (Al9FeNi), can be used in facilities encountering particle erosion. The aim of this study was thus to explore its erosion characteristic. According to the test results, the wear process is governed by ductile mode although it is also associated with brittle cracking of the second phase particles. Friction stir process can improve the erosion resistance by refining the coarse particles to suppress their chance of brittle cracking, also by dispersion strengthening of the otherwise coarse dendritic alpha-Al matrix. Further strengthening of alpha-Al by peak-aging (T4/T6) treatment leads to shifting of the impact angle of maximum erosion rate from 20 degrees to 25 degrees. The erosion resistance is generally raised by peak aging, except for some erosion conditions which are affected by shifting of the angle of maximum erosion rate. (C) 2012 Elsevier Ltd. All rights reserved.